MOTOR AND CYCLE

Taranaki Daily News, 12 February 1918, Page 3

MOTOR AND CYCLE

KEWS AND NOTES. ; The differences between British and American methods arc well exemplified ill tiie ease of the Aircraft engine known as the "Liberty'' motor, which is now being produced in large numbers in the United States. Great Britain has been bungling along under dual producing numerous types of air engines, which, from time to time, are altered under the influence of men who consider themselves born goniuses. This memjft <1 hopeless delay in output and ivastly greater expense. 11l America they tackfed tiie matter in a very different manner. They realised that ti v.as ncessary to s+andardis the engine, and the one which they have produced is tho result of the combined experience of over twenty Airerican engineers. 200 of thir best draughtsmen, and twelve different factories; no doubt also they have benefitted toy the mistakes and successes made by the British. The drawings were hegun on June 3, and the first engine was erected twenty-eight days later. Thirty davs after the tests were carried out and proved quite satisfactory. Every part of the engine has been standardised so that it. can be produced in a number of factories throughout the country and cai> be quickly assembled, either in the factories where it has 'been made or at a central works. I have ti ever been able to fatham, says an English writer,-why the unit system of construction has not appealed to the motor-cycle manufacturer. It is an established fact that the transmission problem is greatly simplified, and ft vast improvement in weather proofing and appearance, with material reduction in the cost of production are gained by combining the engine and gearbox. Yet, ap'art from a few exclusive examples such as the Veloce, Clyno two-stroke, Henderson and Diamond, the practice has received hut little favor. The popularity of the countershaft gear and two-step drive is indeed well established, and I am afraid it will remain unshaken until the advetn of the four-cylinder engine. The opposed twin, in the era of which we are now living is a type of engine ttyt does not lend itself as readily to the unit construction as the little four; nevertheless, some improvement could be effected in opposed design iby combining the engine a™d gearbox. At present, these horizontal engines have about four pinion wheels in the timing chest—the main and camshaft pinions, magneto and intermediate wheela, a. sprocket, chain wheel and chain for the first step of the transmission, and six pinions in the three-speed gearbox. In all there are IS piece 9 of meehan ism, all absorbing power, costing money to produce, and spoiling the appearance of the whole machine, for, being attached here and there, they give the impression of afterthoughts necessarily added rattier than of being embodied in the original design. By utilising the timing gear wheels and camshaft as one step of the transmission, and adding but three mofe gearwheels! it is possible to obtain the same end'and much better resuls—fts all is totally en-closed-'-with the saving <sf two pinions, a Main wheel, sprocket and chain. Nor , does the advantage end here, for the life of the pinion wheels and gears, if constructed of the correct material in the first place, greatly exceeds that of the chains. Indeed, I have, used for three seasons a three-speed that ha* not had a single replacement, yet several chains, and sprockets, and, it I remember rightly, two chain wheels, cried "enough" in the same period. There is no end"to the advantages of unit construction. Of course, it will be argued that chains give greater efficiency. Admittedly, but only for such time as they remain in a perfect or new condition. Immediately, wear or stretch takes place and the chain commences to "ride," even imperceptibly, the percentage of efficiency drops much below that of a correctly cut gear wheel. It" is because of all these points that I cannot understand why manufacturer's 'have not thrust the unit construction upon us years ago. An idea of how the petrol shortage in England is forcing motorists to the use of coal gas aB a substitute can be gathered from the fact that one of the big makers of gas containers in England had nearly 8000 orders in hand when the last mail left. The use of coal gas is now threatening to assume such .'proportions that in some quarters fear is expressed that even this substitute may be "limited" b? tiie Govenuwtt.